package com.darsn.fowtle.core.repository.hibernate;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.BeanInitializationException;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.dao.DataAccessException;
import org.springframework.dao.DataAccessResourceFailureException;
import org.springframework.orm.hibernate3.HibernateTemplate;
import org.springframework.orm.hibernate3.SessionFactoryUtils;

public abstract class AbstractHibernateRepository implements InitializingBean {

	private HibernateTemplate hibernateTemplate;

	/** Logger available to subclasses */
	protected final Log logger = LogFactory.getLog(getClass());

	public final void afterPropertiesSet() throws IllegalArgumentException,
			BeanInitializationException {
		// Let abstract subclasses check their configuration.
		checkDaoConfig();

		// Let concrete implementations initialize themselves.
		try {
			initDao();
		} catch (Exception ex) {
			throw new BeanInitializationException(
					"Initialization of DAO failed", ex);
		}
	}

	/**
	 * Concrete subclasses can override this for custom initialization behavior.
	 * Gets called after population of this instance's bean properties.
	 * 
	 * @throws Exception
	 *             if DAO initialization fails (will be rethrown as a
	 *             BeanInitializationException)
	 * @see org.springframework.beans.factory.BeanInitializationException
	 */
	protected void initDao() throws Exception {
	}

	/**
	 * Set the Hibernate SessionFactory to be used by this DAO. Will
	 * automatically create a HibernateTemplate for the given SessionFactory.
	 * 
	 * @see #createHibernateTemplate
	 * @see #setHibernateTemplate
	 */
	@Autowired
	public final void setSessionFactory(SessionFactory sessionFactory) {
		if (this.hibernateTemplate == null
				|| sessionFactory != this.hibernateTemplate.getSessionFactory()) {
			this.hibernateTemplate = createHibernateTemplate(sessionFactory);
		}
	}

	/**
	 * Create a HibernateTemplate for the given SessionFactory. Only invoked if
	 * populating the DAO with a SessionFactory reference!
	 * <p>
	 * Can be overridden in subclasses to provide a HibernateTemplate instance
	 * with different configuration, or a custom HibernateTemplate subclass.
	 * 
	 * @param sessionFactory
	 *            the Hibernate SessionFactory to create a HibernateTemplate for
	 * @return the new HibernateTemplate instance
	 * @see #setSessionFactory
	 */
	protected HibernateTemplate createHibernateTemplate(
			SessionFactory sessionFactory) {
		return new HibernateTemplate(sessionFactory);
	}

	/**
	 * Return the Hibernate SessionFactory used by this DAO.
	 */
	public final SessionFactory getSessionFactory() {
		return (this.hibernateTemplate != null ? this.hibernateTemplate
				.getSessionFactory() : null);
	}

	public final void setHibernateTemplate(HibernateTemplate hibernateTemplate) {
		this.hibernateTemplate = hibernateTemplate;
	}
	
	/**
	 * Return the HibernateTemplate for this DAO, pre-initialized with the
	 * SessionFactory or set explicitly.
	 * <p>
	 * <b>Note: The returned HibernateTemplate is a shared instance.</b> You may
	 * introspect its configuration, but not modify the configuration (other
	 * than from within an {@link #initDao} implementation). Consider creating a
	 * custom HibernateTemplate instance via
	 * <code>new HibernateTemplate(getSessionFactory())</code>, in which case
	 * you're allowed to customize the settings on the resulting instance.
	 */
	public final HibernateTemplate getHibernateTemplate() {
		return this.hibernateTemplate;
	}

	protected final void checkDaoConfig() {
		if (this.hibernateTemplate == null) {
			throw new IllegalArgumentException(
					"'sessionFactory' or 'hibernateTemplate' is required");
		}
	}

	/**
	 * Obtain a Hibernate Session, either from the current transaction or a new
	 * one. The latter is only allowed if the
	 * {@link org.springframework.orm.hibernate3.HibernateTemplate#setAllowCreate
	 * "allowCreate"} setting of this bean's {@link #setHibernateTemplate
	 * HibernateTemplate} is "true".
	 * <p>
	 * <b>Note that this is not meant to be invoked from HibernateTemplate code
	 * but rather just in plain Hibernate code.</b> Either rely on a
	 * thread-bound Session or use it in combination with
	 * {@link #releaseSession}.
	 * <p>
	 * In general, it is recommended to use HibernateTemplate, either with the
	 * provided convenience operations or with a custom HibernateCallback that
	 * provides you with a Session to work on. HibernateTemplate will care for
	 * all resource management and for proper exception conversion.
	 * 
	 * @return the Hibernate Session
	 * @throws DataAccessResourceFailureException
	 *             if the Session couldn't be created
	 * @throws IllegalStateException
	 *             if no thread-bound Session found and allowCreate=false
	 * @see org.springframework.orm.hibernate3.SessionFactoryUtils#getSession(SessionFactory,
	 *      boolean)
	 */
	protected final Session getSession()
			throws DataAccessResourceFailureException, IllegalStateException {

		return getSession(this.hibernateTemplate.isAllowCreate());
	}

	/**
	 * Obtain a Hibernate Session, either from the current transaction or a new
	 * one. The latter is only allowed if "allowCreate" is true.
	 * <p>
	 * <b>Note that this is not meant to be invoked from HibernateTemplate code
	 * but rather just in plain Hibernate code.</b> Either rely on a
	 * thread-bound Session or use it in combination with
	 * {@link #releaseSession}.
	 * <p>
	 * In general, it is recommended to use {@link #getHibernateTemplate()
	 * HibernateTemplate}, either with the provided convenience operations or
	 * with a custom
	 * {@link org.springframework.orm.hibernate3.HibernateCallback} that
	 * provides you with a Session to work on. HibernateTemplate will care for
	 * all resource management and for proper exception conversion.
	 * 
	 * @param allowCreate
	 *            if a non-transactional Session should be created when no
	 *            transactional Session can be found for the current thread
	 * @return the Hibernate Session
	 * @throws DataAccessResourceFailureException
	 *             if the Session couldn't be created
	 * @throws IllegalStateException
	 *             if no thread-bound Session found and allowCreate=false
	 * @see org.springframework.orm.hibernate3.SessionFactoryUtils#getSession(SessionFactory,
	 *      boolean)
	 */
	protected final Session getSession(boolean allowCreate)
			throws DataAccessResourceFailureException, IllegalStateException {

		return (!allowCreate ? SessionFactoryUtils.getSession(
				getSessionFactory(), false) : SessionFactoryUtils.getSession(
				getSessionFactory(),
				this.hibernateTemplate.getEntityInterceptor(),
				this.hibernateTemplate.getJdbcExceptionTranslator()));
	}

	/**
	 * Convert the given HibernateException to an appropriate exception from the
	 * <code>org.springframework.dao</code> hierarchy. Will automatically detect
	 * wrapped SQLExceptions and convert them accordingly.
	 * <p>
	 * Delegates to the
	 * {@link org.springframework.orm.hibernate3.HibernateTemplate#convertHibernateAccessException}
	 * method of this DAO's HibernateTemplate.
	 * <p>
	 * Typically used in plain Hibernate code, in combination with
	 * {@link #getSession} and {@link #releaseSession}.
	 * 
	 * @param ex
	 *            HibernateException that occurred
	 * @return the corresponding DataAccessException instance
	 * @see org.springframework.orm.hibernate3.SessionFactoryUtils#convertHibernateAccessException
	 */
	protected final DataAccessException convertHibernateAccessException(
			HibernateException ex) {
		return this.hibernateTemplate.convertHibernateAccessException(ex);
	}

	/**
	 * Close the given Hibernate Session, created via this DAO's SessionFactory,
	 * if it isn't bound to the thread (i.e. isn't a transactional Session).
	 * <p>
	 * Typically used in plain Hibernate code, in combination with
	 * {@link #getSession} and {@link #convertHibernateAccessException}.
	 * 
	 * @param session
	 *            the Session to close
	 * @see org.springframework.orm.hibernate3.SessionFactoryUtils#releaseSession
	 */
	protected final void releaseSession(Session session) {
		SessionFactoryUtils.releaseSession(session, getSessionFactory());
	}

}
